Tetramethylarsonium ion

Plaice, oysters, mussel samples Arsenic Nine organic arsenic species HPLC with ion spray, MS-MS 0.09jug g"1 tetramethylarsonium ion by MS-MS Corr and Larsen (1996)... 

Byrne et al. (1995), in a study of arsenic-accumulating mycorrhizal and saprophytic mushrooms, identified and confirmed the presence of methylarsonic acid, arsenite, arsenate, dimethylarsinic acid and arsenobetaine. This was the first reported occurrence of arsenobetaine in terrestrial biota. In a more extensive investigation (Svlejkovec et al., 1997) in which 50 mushroom species from five countries, across three continents, were studied, arsenocholine and tetramethylarsonium ion, (CH3)4As+, were found in addition to the other arsenic species... 

Geiszinger, A.E., Goessler, W., Francesconi, K.A. (2002). Biotransformation of arsenate to the tetramethylarsonium ion in the marine polychaetes Nereis diversicolor and Nereis Virens. Environ. Sci. Technol. 36 2905-10. 

Leucocoprinus badhamii and Volvariella volvacea, 47 was the major metabolite. Arsenocholine (55) and the tetramethylarsonium ion (53) were present in a few species, generally in low concentrations. Arsenobetaine (54) was the main compound in Sparassis crispa [123]. 

Water-soluble fractions containing 54 were isolated from two species of jellyfish, Aurelia aurita and Carybdea rastonii. Besides arsenobetaine 54 (the major arsenic compound), the tetramethylarsonium ion 53 and arsenocholine 55 were also detected [151, 152]. Nine species of jellyfish, including the two species treated in the previous paper [151], were classified into arsenocholine-rich and arsenocholine-poor species. 

Arsenic compounds were determined in the marine lungworm Arenicola marina collected from Odensee Fjord, Denmark [159]. In contrast to most other marine animals, A. marina contained most water-soluble arsenic in inorganic forms, and arsenobetaine 54 was present as a minor constituent (6% only). Other arsenic compounds detected in A. marina were dimethylarsinate 47 (4%), tetramethylarsonium ion 53 (1.5%), arsenocholine 55 (<1%), and two arsenosugars (56, 57, 1% and 3%, respectively). A new arsenobetaine, i.e. trimethylarsoniopropionate (62), previously only reported in fish, was also present in trace amounts (<1%). 

Arsenic compounds were examined in three marine gastropods from Thailand, Thais bitubercularis, T. distinguenda, and Manila musiva [160], and the presence of arsenobetaine 54 (93-95% of total extractable arsenic), arsenocholine 55 (3.1-4.6%), tetramethylarsonium ion 53 (0.21-2.2%), a new natural product (67), one unknown arsenic compound (each approx. 0.1%), and an unresolved mixture of arsenic compounds (up to 1 %) were observed. 

The tetramethylarsonium ion 53, arsenobetain 54, and arsenocholine 55 were detected in the soft tissues of both the pearl-free and the pearl-containing pearl oysters Pincdata fucata [162]. More than 20 years ago, arsenic-containing sugars 56 and 58 have been isolated from the kidney of the giant clam, Tridacna maxima [163]. Water-soluble arsenic species were determined in the kidney of the Tridacna derasa [164]. A total of fifteen organoarsenic species were identified, and 13 of these possessed... 

Arsenite sodium arsenite Arsenite arsenic trioxide Arsenate sodium arsenate Tetramethylarsonium ion Dimethylarsinic acid Monomethylarsonic acid Arsenocholine Trimethylarsine oxide Arsenobetaine... 

MTs = metallothioneins NMR = nuclear magnetic resonance pKa = negative logarithm of acid dissociation constant PMT = photomultiplier tube QITMS = quadrupole ion trap mass spectrometry SBSE = stir bar sorptive extraction SDS-PAGE = sodium dodecylsulfate polyacrylamide gel electrophoresis Se-Cis = selenocystine Se-Cys = selenocysteine Se-Et = selenoethionine Se-Hcy = seleno-homocysteine Se-Met = selenomethionine SEC = supercritical fluid chromatography TBT = tributyltin TETRA = tetramethylarsonium ion Tf = transferrin TMAsO = trimethylarsineoxide TMSe = trimethylselonium ion TOFMS = time of flight mass spectrometry USN = ultrasonic nebulizer. 

Arsenic is an ubiquitous element which occurs in the form of various chemical species in the environment. In biological tissues, the main species identified is arsenobetaine which is considered to be non-toxic and present at more than 90% in fish tissues but does not exceed 50% in mollucs [128], Other species such as arsenocholine, tetramethylarsonium ion, trimethylarsenoxide, dimethyl-arsinic acid and arsenosugars have also been identified [129-132]. 

Tetramethylarsonium ion is a common arsenic species in marine animals. It is present usually as a minor constituent, although exceptions do occur for example, it is a significant arsenical in several species of bivalve mollusks (1). Traces of tetramethylarsonium ion have been found in some freshwater animals (6). It has also been reported in several fungal species, usually at low levels, and as a trace constiment of some terrestrial plants as well (6). There have been no reports of tetramethylarsonium ion in seawater or freshwater. 

Freshwater plants present a different picture. Here, arsenite and/or arsenate are found as significant or major arsenicals, and arsenosugars are only occasionally detected (30). Methylarsonate and dimethylarsinate are also present in most samples at low levels. Interestingly, tetramethylarsonium ion was also reported in several freshwater plant species, generally as a trace constituent (30). 

Of particular interest, however, is the presence of arsenobetaine as a major arsenical in many species of fungi (20). In addition, several fungal species contain arsenocholine and/or tetramethylarsonium ion, and Sparassis crispa contains arsenocholine as the major arsenical (20). These three arsenic compounds had traditionally been considered metabolites of marine animals before their discovery in fungi. 

An interesting aspect of the work on terrestrial plants is the widespread occurrence of trimethylarsine oxide. It occurs in many of the plants examined so far, and is the major compound in aqueous methanol extracts of Alms incam (26). Arsenobetaine and tetramethylarsonium ion have been detected in several plant species, but the levels are low. Arsenocholine may have been present in some species but this is not proved because it was unresolved from trimethylarsine oxide (120). Arsenosugars (compounds 1 and 2 only in Fig. 2) have been reported in some plants at low levels (15,26). 

Arsenic is abundant in seafood. Arsenobetaine is the major arsenic species present in fish and shellfish. Arsenosugars are the dominant arsenic species in seaweed. Both arsenobetaine and arsenosugars are present in mollusks (bivalves and gastropods) at comparable concentrations. Smaller amounts of arsenocholine, trimethylarsine oxide, tetramethylarsonium ion, DMA(V), MMA(V), inorganic arsenic, and unidentified arsenicals have also been found in seafood. Much less is known about the arsenic species in other food we eat. 

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